Even if a little black dress is a classic that will never go out of style, it's hard to buy just one because there are so many styles to pick from. Lucky for you, Forever21 has many styles, all under $30, so you can buy one in eve...Even if a little black dress is a classic that will never go out of style, it's hard to buy just one because there are so many styles to pick from. Lucky for you, Forever21 has many styles, all under $30, so you can buy one in every shape.